This invention relates in general to optical systems, and, more particularly, to a system and method for providing images for an operator of a vehicle.
During daylight hours, the driver of a vehicle is able to detect and recognize objects that would be difficult, if not impossible, to detect or recognize at night. For example, on a sunny day, a deer approximately 500 meters ahead of a vehicle should be readily detectable and recognizable. At night, however, particularly when the headlights provide the only illumination, the deer will not be detectable, much less recognizable, at that distance because it will be beyond the range of the headlights. Moreover, by the time the driver detects the deer, and well, before recognizing what it is, the vehicle will be much closer to the deer than during daylight. Accordingly, the risk of a resulting accident is much higher at night than during the day.
Consequently, in order reduce the risk of accidents, night vision systems have been developed to supplement the driver""s vision. Typical night vision systems include an infrared camera unit mounted in the grill of the vehicle and an image source mounted in the vehicle""s dashboard. The camera unit gathers information regarding the scene in front of the vehicle, and the image source projects an image derived from the information onto the windshield for display.
Using the windshield for image display, however, has several drawbacks. For example, the illumination of the image may be poor because a large amount of light is lost due to refraction. As another example, the image may be distorted because of the windshield""s varying curvature.
To address these drawbacks, several night vision systems are proposing to use a magnifying optical element mounted to the dashboard as the combiner. Because of vision and aesthetic considerations, however, there is a continuing demand to reduce the size of the combiner. Moreover, if the combiner is to retract into the dashboard when not in use, additional sizing concerns may come into play. Unfortunately, reducing the size of the combiner usually decreases the field-of-view that may be presented to the operator of the vehicle.
In accordance with the present invention, at least some of the disadvantages and problems associated with previous systems and methods for providing images for an operator of a vehicle have been substantially reduced or eliminated. Accordingly, at least in particular embodiments, the invention provides a low-profile combiner for an image display system that has an acceptable field-of-view for the operator.
In particular embodiments, a method for providing images for an operator of a vehicle includes receiving electrical signals representing electromagnetic radiation at an image source and generating a visual image based on the electrical signals. The method also includes reflecting different portions of the visual image with a magnifying optical element for presentation at different viewing locations, the visual image appearing as a virtual image, wherein at least one dimension of the visual image is larger than the magnifying optical element can use to present an image at one of the viewing locations.
In certain embodiments, a system for providing images for an operator of a vehicle includes an image source and a magnifying optical element. The image source is operable to receive electrical signals representing electromagnetic radiation and to generate a visual image based on the electrical signals. The magnifying optical element is operable to reflect different portions of the visual image for presentation at different viewing locations, the visual image appearing as a virtual image, wherein at least one dimension of the visual image is larger than the magnifying optical element can use to present an image at one of the viewing locations.
The present invention has several technical features. For example, in some embodiments, the invention allows more of a visual image to be observed than the optical configuration will allow at one viewing location. Thus, an adequate view of the scene outside the vehicle may be achieved even when optical considerations do not allow complete viewing of the scene at one viewing location. As another example, in certain embodiments, the distracting features of the border effect are attenuated and/or distortions and/or aberrations caused by imperfections at the edge of the optics are reduced. As a further example, in particular embodiments, a combiner for the system may be reduced substantially in size while still allowing an operator to observe an adequate field. Thus, viewability and packaging constraints may be achieved.
Of course, some embodiments may possess none, one, some, or all of these technical features and/or additional technical features. Other technical features will be readily apparent to those skilled in the art from the following figures, written description, and claims.